As for the present non-excavation field, the common reaming method is to apply drilling machine to drive the drilling rod and reamer when reaming hole with a diameter of 100 mm or larger. Due to frictions caused by the drilling rod and hole when rotating, the most part of the driving force provided by the drilling machine is consumed by the rotation of drilling rod whilst only small part of force is used for reaming via reamer. Thus the reaming method mentioned herein is not efficient. In order to solve the problem of consumption of driving force by rotation of drilling rod, a type of reaming tool appears from present technology, which utilizes hydraulic pump to drive power section assembly so as to force the rotation of reamer for the realization of reaming. The reaming tool contains power section assembly, driving shaft and reamer, and the rotor from power section assembly connects to reamer via driving shaft. The drilling liquid with high pressure from hydraulic pump via liquid inlet of power section assembly comes into screw cavity formed between stator and rotor and then comes out from liquid outlet of power section assembly with low pressure. Through the pressure difference, the drilling liquid drives rotor to rotate and then the rotor forces reamer to rotate via driving shaft for the realization of reaming. As for the reaming tool, only reamer rotates and the energy (or called work) is mostly used for reaming, which solves the problem that the consumption of driving force during the rotation of drilling rod when drilling machines drives reamer for reaming. However, due to the flexible connection of driving shaft to power section assembly and reamer and because of the incompact structure caused by the certain length of driving shaft, the driving shaft is not capable of bearing large torque, which frequently leads to the fracture of driving shaft while reaming. Hence, the drilling tool is not capable of providing a large torque to ream holes with large diameter because of the unsatisfactory strength of the tool.